Increasing freight transport speed has also imposed the technical adaptation of wagons so as to cope with speeds of up to 160 km/h. Therefore, for the Inter Cargo Express freight service, German railway operator DB has bought DRSS-bogie container wagons for maximum speeds of 160 km/h as early as 1991.
Germany’s initiative in terms of railway high-speed freight transport was technically different from that of France (TGV Fret). The aim of this initiative was faster transport with rather heavy freight trains compared to TGV Postal.
When the high-speed lines between Hanover and Würzburg and Stuttgart and Mannheim were opened, German Railways (DB) introduced the Inter Cargo Express service, primarily intended for intermodal transport (for example, maritime containers). Therefore, in June 1991, services began on the Bremen-Stuttgart and Hamburg-Munich routes. The trains operated at 160 km/h thus reducing the running time by 2 hours to about 8 hours between Bremen and Stuttgart and 9 hours between Hamburg and Munich.
The trains consisted of 20 four-axle container wagons. The trains had a gross weight of 900 tonnes with a payload of 500 tonnes and were hauled by BR 120 series locomotives.
Type of wagons used for express freight trains
Once the Inter Cargo Express service was introduced, German operator DB equipped its rolling stock fleet with flat wagons for the transport of Sgss-y 703 series containers (fig. 1) fitted with DRSS series Talbot bogies for maximum speeds of 160 km/h.
The chassis of the wagon is identical with that of conventional wagons, however, in order to insure containers, the wagons were fitted with automatically vertical-locking container pins.
Description of the bogie used for class Sgss-y 703 wagons
To negotiate the necessary braking distance for a train to stop from the speed of 160 km/h, the bogies have been fitted with a braking system with brake discs (as we all know, the brake block system is inefficient at speeds superior to 140 km/h). Thermal calculations have revealed that it is necessary to equip the bogie with three brake discs on each wheelset (fig. 2) so as to spread the high amount of energy compared to passenger cars running at speeds of 200 km/h and which have only two brake discs on each wheelset. Overall, the bogie has 6 brake discs and just as many brake cylinders.
The bogie frame (fig.3) consists of two solebars, two frontal beams and a median beam. The pin which conveys forces between the bogie and the rest of the wagon is introduced in the median beam. The same median beam bears the brake cylinders and calipers. The fastening beams of the axle suspension (primary suspension) are welded on the solebars. They convey forces from the wheelsets to the bogie frame.
The primary suspension (fig.4) is ensured by double ring rubber springs. Friction elements similar to those used for Y 25 bogies are used to dump vibrations. This type of suspension confers the vehicle a superior running behaviour compared to the wagons with laminated spring suspension.
New DRRS 25 L
An improved variant of the DRRSss-y bogie was presented in 2012 at InnoTrans – the new class DRRS 25 L bogie (fig. 5). It is also built by Talbot (now part of Alstom) as a development of the DRRSss-y bogie. Its suspension and bogie frame are similar to those of the previous bogie. The difference between the two variants consists of the two brake discs instead of three. The advantage of using only two brake discs instead of three consists in reducing the non-suspended mass and thus the wear of the rolling set and of the rolling track and increasing the quality of the rolling behaviour. This has been made possible by using superior materials for brake discs and brake linings as they resist to superior thermal conditions.
References:
1 Gerhard Troche – ‘’High-speed rail freight’’ Sub-report in Efficient train systems for freight transport, KTH Railway Group, Stockholm 2005
2 Prof. Dr.-Ing. Markus Hecht – ‘’Wear and Energy Saving Bogie Design with Rubber Primary Springs – Principles and Experiences’’, Kiruna, Sweden June 11 – 13, 2007
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